The invention relates to a hypodermic syringe, consisting of a syringe body and a cylindrical ampoule inserted therein, which is provided with a Luer-Lock connection for a cannula, the threaded part of the connection being at one end of the syringe body.
In such known hypodermic syringes to be found on the market the Luer-Lock connection with its socket-like internal thread is sometimes fitted with a subsequently installed cone. This Luer-Lock design does not guarantee secure connection between the cannula and the Luer-Lock cone by means of the cannula-side connecting piece which interacts with the threaded section because, when screwing the connecting piece into the thread, the cone can be displaced to one side and, as a result, a firm and tight connection between the cone and the connecting piece of the cannula is no longer possible, so that the contents of the ampoule can escape between these two parts.
Furthermore, the cone of the Luer-Lock connection mounted on the syringe body is provided with a transfer cannula, by means of which a diaphragm seal of the cylindrical ampoule is penetrated when pushing the former in the direction of the cone, as a result of which a passage from the interior of the ampoule to the cannula is produced. As a consequence of this penetration of the diaphragm seal, minute particles of the diaphragm are often broken away, so that an unfragmented connection between cannula and cylindrical ampoule cannot take place.